Our program seeks to clarify cellular and molecular mechanisms that lead to chronic asthma in order to identify novel, more effective therapies. We concentrate on immune mechanisms that underlie chronic airway inflammation with a clear focus on one immune tolerance molecule, the class I major histocompatibility complex protein human leukocyte antigen (HLA)-G, that we believe has an important role in modulating airway inflammation that is critical to chronic asthma. The key premise of our AADCRC proposal is that understanding the role of HLA-G will lead to new and better therapies to alleviate the suffering caused by asthma. To this end we propose three highly integrated and related projects: in Project 1, we will examine the presence and regulation of expression of HLA-G in asthmatic airways and in the airway epithelium, and relate presence to asthma severity and to the expression of regulating microRNA. We will examine the regulation of HLA-G expression by key Th2 cytokines such as IL-13 that are important to chronic asthma and relate expression back to airway cytokine concentrations in chronic asthma. In Project 2, we will exploit naturally occurring genetic variations in HLA-G and its LILRB receptors to understand how signaling through HLA-G and its receptors regulate the transition of CD4+ lymphocytes to the Th2 phenotype in mild/moderate asthma and to the Th17 phenotype in severe asthma. This project also will examine how genetic variation in the LILRB receptors modulate the effects of HLA-G on both T cell phenotype and on the SHP1 and SHP2 signaling pathways that modulate airway smooth muscle hypertrophy in chronic asthma. In Project 3, we will elucidate mechanisms that account for the higher risk of asthma among children of asthmatic mothers compared to children of non-asthmatic mothers. Using HLA-G as a model of the interactions of genotype and asthma status in mother and child, we will identify differentially expressed genes and the mechanisms for their differential expression in airway epithelium, CD4+ T cells and airway smooth muscle in subjects with chronic asthma. To complete these projects, each will interact with a robust Patient Recruitment and Data Analysis Core that will recruit 100 carefully phenotyped and genotyped asthmatic subjects and additional control subjects, and collect blood and airway biological specimens to be used in each project through a Lung Biological Specimens Core that will provide analytical and long-term storage. We believe that our current levels of productivity and collaboration combined with new, exciting and cutting-edge questions in this proposal will allow us to be successful in achieving our overall goal - identifying novel therapeutic targets for chronic asthma.